Interferometer

An interferometer comprising:

• an analysis unit;
• and
• a length measurement unit, wherein
• the analysis unit includes
• an analysis optical system that includes a first light source configured to emit an analysis light, a moving mirror configured to reflect the analysis light, and a first light receiving element configured to receive the analysis light and output a first received light signal, and that is configured to analyze a sample using interference of the analysis light, and
• a mirror drive unit configured to drive the moving mirror based on a mirror drive signal,
• the length measurement unit includes
• a length measurement optical system that includes a laser source configured to emit a laser beam, a light modulator configured to add a modulation component by modulating a frequency of the laser beam using a vibrating element, and a second light receiving element configured to receive the laser beam including a length measurement component generated by irradiating the moving mirror with the laser beam, and the modulation component, and output a second received light signal, and that is configured to detect a position of the moving mirror using interference of the laser beam, and
• the vibrating element is a signal source of the mirror drive signal.